Non-environmentally hazardous, non-volatile adhesive promoter composition for curing adhesives

ABSTRACT

A non-environmentally hazardous, non-volatile adhesive promoter composition useful in promoting the cure and/or enhancing adhesion of adhesives and for use in combination with adhesive bond polymerization. The promoter composition is a combination of a fluid carrier that remains substantially present during the curing of an adhesive composition and an active component capable of promoting the cure and/or enhancing adhesion of the adhesive and being miscible in the fluid carrier.

FIELD OF THE INVENTION

This invention relates to a non-environmentally hazardous andnon-volatile adhesive promoter composition for promoting the cure ofadhesives and for use in combination with adhesive compositions. Moreparticularly, the present invention relates to an adhesive promotercomposition which includes a fluid carrier that remains substantiallypresent during the curing of the adhesive composition and an adhesivepromoter component capable of promoting the cure of the adhesivecomposition and being miscible in the fluid carrier.

BACKGROUND OF THE INVENTION

Chlorinated hydrocarbons such as 1,1,1-trichloroethane and chlorfluorohydrocarbons (CFC), such as C₂ F₃ Cl₃ also known as FREON®, have beenused for many years as solvents in numerous applications. Thesematerials have shown to be very useful in the preparation and deliveryof activator and accelerator compositions used in the adhesive field. Inrecent years, the use of these compounds has been substantially lesseneddue to their deleterious effect on the environment. Regulations havebeen promulgated not only in the United States but in countriesthroughout the world to accelerate the phase-out of environmentallydestructive solvents, and in particular those which are believed to beozone-depleting substances. In addition to laws designed to prevent theuse of these substances, product labelling requirements have also beenpromulgated to insure notice is given as to those compounds used asalternatives. Finding acceptable alternatives, however, has been anextremely difficult task. For example, in applications such as adhesiveaccelerator compositions, the solvent should possess high chemicalstability, non-flammability, low toxicity, yet be sufficiently volatileto readily evaporate once applied to leave the active ingredient, e.g.an amine accelerator or activator, on the surface to which it isapplied. In addition to these requirements, consideration must be givento cost factors which are critical to commercial development.

Attempts to find good solvent systems which are non-ozone depleting,non-flammable, yet sufficiently volatile, have not been entirelysuccessful. Although many materials have possessed certain of thesecharacteristics, many have been deficient in the majority of theseproperties. For example, materials such as heptane, acetone, methylethylketone, isopropanol, and methanol are excellent solvent systems, withexcellent volatility, i.e. low flash point temperatures and high vaporpressures, but are extremely flammable. Other substances such asisoparaffins, and propylene glycol ether are less flammable, but arestill combustible and evaporate slower.

In co-assigned and co-pending U.S. Ser. No. 08/322,937 filedconcurrently herewith, one solution offered for the replacement ofozone-depleting CFC carriers in adhesive promoter compositions was aunique co-solvent composition comprising an azeotropic mixture of aperfluorocarbon compound and an alkylsiloxane. This co-solvent solutionwas non-ozone depleting and possessed the required characteristics to beuseful as a carrier for adhesive promoter compounds, includingactivators, accelerators, initiators and the like for promoting cure orenhancing adhesion of cyanoacrylate adhesives.

It is conventional in the art of adhesive promoters, i.e. accelerators,activators, initiators and the like, that they be carried in volatilesolvents when used as separate components in conjunction with adhesivecompositions. In the case of cyanoacrylate adhesives, accelerators aregenerally applied to a substrate surface prior to application of theadhesive. These adhesive promoter compositions, sometimes also referredto as primer compositions, are usually comprised of amine compoundsdissolved in a CFC solvent, or 1,1,1-trichloroethane, which as discussedabove is no longer considered an environmentally safe material due toits ozone-depleting nature.

Numerous patents describe the use of volatile solvents as carriers foradhesive promoter compositions, such as activators, accelerators and thelike. Such adhesive promoter compositions are used in conjunction withthe cure of cyanoacrylate adhesives, olefinic adhesives, anaerobicadhesives and two-part acrylic systems. For example, U.S. Pat. No.3,260,637 describes a method of bonding a cyanoacarylate adhesive usingamines dissolved in a volatile carrier solvent preferably having aboiling point below about 100° C. U.S. Pat. No. 4,822,426 discloses aprimer solution consisting of an organometallic compound combined with afluorine-containing compound, for use with difficult to bond tonon-polar resins, such as polyolefins. The primer composition is appliedwith a volatile solvent.

U.S. Pat. No. 3,836,377 discloses an adhesive composition which consistsof a monomeric ester of cyanoacetic acid and a polymerizationaccelerator which can be applied by means of a volatile solvent. U.S.Pat. No. 4,979,993 teaches the use of a primer composition consisting ofa tertiary ammonium carboxylate compound carried by a low surfacetension organic solvent. This reference also teaches that the solventshould readily evaporate to allow for the reaction of the primer withthe adhesive.

In two-part adhesive compositions, where a curable component is presentin one part and a curing agent is present in a second part, the curingagent and/or accelerator is generally applied with vehicles such aslower alcohols and in some cases water. For example, see U.S. Pat. No.4,460,759, which teaches the removal of the solvent prior to bringingthe surfaces together to initiate the bonding reaction.

U.S. Pat. No. 4,933,234 discloses primed polymeric substrates having atleast one organic nucleophilic graft-polymerizable monomer or saltthereof grafter thereon. Various amine-bearing monomers are disclosedand the monomer compositions may be applied using solvents, crosslinkingagents and surfacts.

Additionally, cyanoacrylate adhesives have incorporated a variety ofadditives directly into the adhesive composition per se to strengthenthe bond. These additives have conventionally been directly incorporatedinto the adhesive composition and are not handled as a separatecomponent, in contrast to typical accelerator and activatorcompositions. These additives, in the case of U.S. Pat. No. 4,139,639included an adhesion promoter of the formula: ##STR1## wherein R' ishydrogen or an alkyl, aryl or cycloalkyl group having 1 to 10 carbonatoms. The formal name given to this class of compounds is3,4,5-trihydroxybenzoic acid or esters thereof. In addition to theadhesion promoter, an inhibitor is also added to the cyanoacrylateadhesive composition to stabilize the mixture from prematurely curing.

U.S. Pat. No. 2,784,127 discloses cyanoacrylate adhesive compositionswhich are plasticized by the addition of alkyl ester in aliphaticdicarboxylic acid of the formula, R₁ OOC--(CH₂)_(n) --COOR₁ wherein n isa whole integer in the range of 1-8 and R₁ is an alkyl group from 1 to 8carbon atoms. Also disclosed are alkyl phosphates in which each alkylgroup contains from 1 to 8 carbon atoms, as well as triaromaticphosphates such as triphenylphosphate and tricresyl-phosphate. Theseplasticizers are dissolved in the monomeric cyanoacrylate adhesive toprevent failure of the adhesive bond after aging. Up to about 20% of theplasticizers are disclosed as being incorporated. The plasticizersallegedly function to add flexibility to the bond without adverselyaffecting the degree of adhesion. No disclosure is given to the additionof a promoter component into the adhesive composition per se.

As is evident from the discussion, the art is replete with examples ofvolatile solvents as carriers for adhesion promoter compositions. Thisis the case whether the adhesion promoter be an activator, accelerator,catalyst or initiator system. Solvents have not historically beenwelcome in the bonding process since they weaken the adhesive bond,interfere with the adhesive bonding process, prevent contact between theadhesive and the substrate and in some instances, attack the adhesiveand/or the substrate.

The present inventor has discovered that using a fluid carrier otherthan a volatile solvent to dissolve the active component, carry it tothe substrate and incorporate itself into the adhesive compositionduring bonding, alleviates these difficulties. Thus, rather thanapproach the environmental problem of ozone depletion using a non-ozonedepleting volatile solvent, the present invention utilizes asubstantially non-volatile fluid carrier which is miscible in thepromoter, delivers the promoter component to the substrate surface andremains incorporated in the adhesive.

It is clear that there is a need for such a non-volatile, non-ozonedepleting fluid carrier which is capable of sufficiently carrying theadhesive promoter component to the substrate surface, as well as beingincorporated into the adhesive composition during the bonding processwithout interfering with polymerization.

SUMMARY OF THE INVENTION

The present invention is directed to an adhesive promoter compositionfor promoting the cure and/or enhancing the adhesion of adhesivecompositions that includes a fluid carrier, which remains substantiallypresent during the cure of the adhesive composition, and an adhesivepromoter component being miscible in said fluid carrier and beingcapable of promoting the cure of the adhesive composition. The fluidcarrier of the adhesive promoter composition is substantiallynon-volatile and remains incorporated in the adhesive composition duringcure. The adhesive promoter component can be any active ingredient thatis used to prepare a surface for bonding or to promote the curing of theadhesive in the bonding process. For purposes of this invention, theterm "active" will mean the adhesive promoter component. The activecomponent is combined with the non-volatile fluid carrier to comprisethe adhesive promoter composition. For example, in a preferredembodiment of the present invention, the adhesive promoter component istypically an amine or amino-bearing compound used to cure cyanoacrylateadhesive compositions. Other examples include organometallic compoundsused as primers for anaerobic adhesive compositions.

As previously described, activator compositions typically used inconjunction with these types of adhesive compositions employ volatilesolvents to carry the activator component to the substrate surface. Thepresent invention clearly represents a departure from solvent carrierswhich served only to transport the active and were subsequently removedor flashed-off prior to contacting the adhesive composition. Rather, thepresent invention employs a non-volatile fluid carrier whichparticipates not only by transporting the promoter component, but alsoby further serving to plasticize the adhesive composition during cure.In a preferred embodiment, the fluid carrier has at least oneunsaturated molecular bond present to overcome the tendency of certainsaturated esters from attacking particular plastic substrates.

The non-volatile fluid carrier is generally an ester having a boilingpoint about 100° C. or more and which is fluid at room temperature.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS

Adhesive promoter compositions of the present invention provide a novelapproach to the curing of adhesive compositions in adhesive bonding. Thepromoter composition includes a substantially non-volatile fluid carrierthat remains present during the curing of an adhesive composition and anadhesive promoter component being miscible in the fluid carrier andbeing capable of promoting the cure and/or enhancing the adhesion of anadhesive composition. Rather than functioning like conventional volatilesolvents, as temporary carriers which are intended to evaporate once theactivator component is deposited, the fluid carrier of the presentinvention is incorporated into the adhesive composition. Thus, whereasconventional solvents negatively affected the cure and bonding ofadhesives to substrates, the present compositions contribute in apositive way to the overall properties of the adhesive. These effectsare in addition to the environmental advantages obtained because thefluid carrier does not evaporate or cause undesirable waste product.

For purposes of this invention, the term "promoter composition" is meantto be interpreted in the broadest sense as including accelerating,activating, initiating and other adhesive promoting compositions whichmay be used in two part systems and applied to the surface of asubstrate prior to contacting the substrate with an adhesive. Also forpurposes of this invention, the term "non-volatile" will mean that theboiling point of the ester is about 100° C. or greater.

Although the function of the fluid carrier once incorporated into theadhesive composition is not fully understood, and without wishing to bebound by any one theory, it is believed that the fluid carrier serves toplasticize the adhesive. The fluid carrier thus serves as a usefuladditive in the adhesive composition, in addition to serving its primarypurpose of transporting the adhesive promoter component onto thesubstrate.

More specifically, the non-volatile fluid carrier may be selected fromthe group consisting of esters which have a boiling point of about 100°C. or greater and which are fluid at room temperature. These esters maybe formed from the reaction of alkyl or aromatic carboxylic acids withalkyl or aromatic alcohols. Other methods of preparing esters useful inthe present invention are also contemplated. More specifically, thefluid carrier is preferably selected from the group consisting of anacetic ester of a C₃ -C₁₈ alkyl alcohol, an acetic ester of a C₂ -C₁₈alkenyl or aryl alcohol, an acetic ester a C₃ -C₁₈ allyl alcohol, anacetic ester of a C₇ -C₁₈ alkaryl alcohol, an acetic ester of a C₇ -C₁₈aryalkyl alcohol and mixtures thereof. The aforementioned esters areparticularly useful due to their commercial availability and ease ofuse.

Other useful non-volatile fluid carriers contemplated within the scopeof the present invention include those formed from the reaction ofaromatic carboxylic acids, such as phthalic acid, with alkyl alcohols.Diethyl phthalate, dipropyl phthalate, dibutyl phthalate and dioctylphthalate are typical examples of these. Other useful esters includeesters of aromatic alcohols with alkyl carboxylic acids, such as linalylacetate, and phenethyl acetate.

The fluid carrier may also be a benzoic diester of an alkyl glycol ofthe formula:

    OH--(C.sub.x H.sub.2x O).sub.n --H

wherein x is 2-3 and n may be 1 up to about 10, provided the glycolremains fluid at about room temperature. Non-limiting examples includeethylene glycol dibenzoate, diethylene glycol dibenzoate, propyleneglycol dibenzoate, dipropylene glycol dibenzoate and mixtures thereof.

In addition, the fluid carrier may also be an acetic ester of phenol.

It is preferred that the fluid carrier have at least one unsaturatedbond present. This is to prevent the tendency of saturated esters toattack certain plastic substrates. It has been found that whenunsaturated bonds are present, this tendency is alleviated. Sinceplastic substrates are a primary bonding surface for many adhesives,particularly cyanoacrylate adhesives, this feature is important in theseapplications.

The active component of the promoter compositions may be selected from awide variety of adhesive promoter compounds and materials. Theparticular promoter component will, of course, depend on the adhesivecomposition to be employed and the function of the component, as well asthe type of substrate to be bonded. Cyanoacrylates, anaerobics,acrylics, epoxies and olefins each have classes of compounds whichactivate, accelerate or otherwise promote their cure and/or enhanceadhesion.

The fluid non-volatile carriers of the present invention have been foundto be particularly useful with activator compounds for use withcyanoacrylate adhesive compositions. Cyanoacrylate adhesives are rapidsetting materials which have excellent utility in bonding a variety ofmaterials. The polymerization of cyanoacrylate adhesives is catalyzedusing anionic materials such as hydroxyl- or amine-containing compounds.In the present invention, these compounds can be selected from a widevariety of materials which include:

a) organic or inorganic substituted and unsubstituted amines such asprimary, secondary and tertiary amines and their salts;

b) N-substituted alkanoamines;

c) acylated N-substituted alkanoamines;

d) polyamines, such as diamines;

e) heterocyclic amines such as the diazabicyclo or triazabicyclocompounds disclosed in U.S. Pat. No. 4,869,772 and having the formulas:##STR2##

f) tertiary ammonium carboxylate compounds disclosed in U.S. Pat. No.5,066,743 and having the formula: ##STR3## wherein R₁, R₂, R₃ and R₄ mayeach vary independently of each other and may be selected from the groupconsisting of alkyl, alkenyl, alkynyl, alkylaryl and arylalkyl, andpreferably wherein at least one of R₁, R₂ and R₃ is a long chain alkylmoiety having 6-20 carbon atoms and R₄ is selected from the groupconsisting of alkyl and alkenyl;

g) phosphazene compounds including ring or chain polymers containingalternating phosphorus and nitrogen atoms, such as disclosed in U.S.Pat. No. 4,496,685;

h) ethylenediamine compounds such as those disclosed in U.S. Pat. No.5,314,562 and having the formula: ##STR4## wherein each R₅, which may bethe same or different, represents hydrogen, an alkyl, alkenyl or alkoxygroup having 1 to 8 carbon atoms, an aryl group having 6 to 8 carbonatoms, a nitrogen-, silicon- or silicon-substituted group having I to 8carbon atoms or a heterocyclic group having up to 8 carbon atoms whichmay be unsubstituted or substituted with hydroxy, ether oxygen orsulphur;

i) quaternary ammonium compounds useful as primers for improving theadhesion, as disclosed in U.S. Pat. No. 5,079,098, having the formula:##STR5## wherein R₁, R₂, R₃, and R₄ may each vary independently of theothers and are selected from the group consisting of alkyl,hydroxyalkyl, aryl, alkaryl, aralkyl and alkenyl, optionally substitutedwith heteroatoms; and A-- is an anion whose pKa value in deprotonationequilibrium reaction is greater than about 0.

Among the preferred class of amines are the acylated N-substitutedalkanoamines such as dimethyl-para-toluidine (DMPT). DMPT has been foundto be particularly useful in the present invention as the activatorcomponent to promote the cure of cyanoacrylate adhesives.

Generally, the promoter component, i.e. active component, is present inthe adhesive promoter composition in amounts which are effective toproduce the required cure speed and tensile strength. The activecomponent of the present invention may be present in amounts of about0.1% to about 10% by weight of the activator composition. Preferably,the activator component is present in the composition in amounts ofabout 0.5% to about 5.0% and most preferably, about 0.5% to about 1.0%by weight. It is preferred to apply the adhesive promoter composition atthe lowest effective concentration to decrease cost and increase ease ofapplication, as well as allow the active to be close to the thickness ofa monomolecular layer. Typically, one application of the activatorcomposition on one side of the substrate is sufficient, but multiplecoatings may of course be applied.

In addition to the fluid carrier and active component, the adhesivepromoter composition may contain other materials and conventionaladditives useful in adhesive promoter compositions. These include,without limitation, stabilizers, viscosity modifiers, odor-maskingagents, coloring agents and the like.

The activator compositions of the present invention can be used onnumerous types of bonding surfaces, such as steel, plastic, glass andwood. These compositions provide a more environmentally-friendlyalternative to conventional solvent-containing adhesive promotercompositions, and do not attack most engineering plastics. Additionally,they are non-ozone depleting, non-flammable and non-combustible.

The adhesive promoter compositions of the present invention may beapplied to the substrate to be bonded in any manner that is satisfactoryto enhance cure speed and/or adhesion of the cyanoacrylate bondant tothe substrate. For example, spraying, dipping, brushing, swabbing,wiping, roller-coating, etc. of the activator composition onto one ormore of the substrate surfaces prior to application of the adhesive ispreferred.

The thickness of the adhesive promoter composition and adhesive layermay vary widely, depending on the character and composition of thesubstrate surfaces, the particular adhesive and active to be employed,as well as the end use of the final bonded assembly. With any given setof parameters, acceptable and optimum thicknesses may be determined bylapshear tensile strength values for particular samples at variousprimer and adhesive layer thicknesses. The adhesive layer of about "0"to about 5 mils and as great as about 10 mils have been found to begenerally satisfactory for most substrates.

Those plastic materials with which the adhesive promoter compositionshave been shown to be effective include, without limitation,polycarbonate, polyphenylene ether alloy, polyphenylene sulfide,polyphenylene oxide, nylon, melamine, polyacetal, polycarbonate,polyesters, acrylic, acrylonitrile butadiene styrene (ABS), celluloseacetate, ethylene, vinyl, acetate (EVA) ionomer, polyarulether,polyethylene, polypropylene, polybutylene, polyallomer,polymethylpentane, polystyrene, polysulfone, polyvinyl chloride (PVC),styrene acrylonitrile (SAN), styrene butadiene, epoxides and phenolics,among others.

Suitable cyanoacrylate adhesives for use with the present invention arerepresented by the general formula: ##STR6## wherein R⁶ is alkyl,alkenyl, cycloalkyl, aryl, alkoxalkyl, aralkyl, haloalkyl or othersuitable group. The lower alkyl alpha-cyanoacrylates are preferred. Inparticular, these include methyl, ethyl, n-propyl, n-butyl, isobutyl,isopropyl, allyl, cyclohexyl, methoxyethyl, methoxypropyl, cyclohexyl,n-pentyl, allyl, and ethoxyethyl cyanoacrylates.

In applications where structural engineering adhesives are employed suchas anaerobic adhesives, the adhesive promoter compositions may containcomponents which interact with the initiator present in the adhesivecomposition to further speed the cure. For example, tertiary alkylamines, rhodamine, organic hydrazides, alkoxy amines, as well asorganometallic compounds such as ferrocene, are conventionally used.

The present invention also contemplates a method of bonding substratesurfaces together with an adhesive composition. This method includestreating a surface of at least one substrate with an adhesive promotercomposition which includes a fluid carrier that remains present duringthe cure of said adhesive composition and an adhesive promoter, i.e.active, component which is capable of promoting the cure or enhancingadhesion of said adhesive composition and is miscible in said fluidcarrier. Subsequent to treatment of the substrate surface with theadhesive promoter composition, an adhesive composition is applied to atleast one of the substrate surfaces, either the treated surface or thenon-treated surface, and bonding of the substrate surfaces iseffectuated by placing them in contact with each other and permittingpolymerization to occur.

In another aspect of the present invention, an adhesive kit comprisestwo parts co-located in a single package whereby the first part includesan adhesive promoter composition comprising a fluid carrier whichremains present during the cure of an adhesive composition and apromoter component which is miscible in said fluid carrier and promotesthe cure and/or adhesion of said adhesive composition; and a second partwhich includes an adhesive composition, the cure of which is promoted bysaid adhesive promoter composition.

The features and advantages of the present invention will be moreclearly understood by reference to the following examples, which areillustrative of certain preferred embodiments, but are not to beconstrued as limiting the scope of the present invention.

EXAMPLES

Adhesive promoter compositions of the present invention, as well ascontrol compositions, were formulated as shown in Table 1, below.Compositions 1-14 represent activator compositions which use thenon-volatile fluid carrier of the present invention.

                                      TABLE 1                                     __________________________________________________________________________    ADHESIVE PROMOTER COMPOSITIONS                                                                    Active                                                                        Component                                                                     (% weight)                                                                           Adhesive Type                                      __________________________________________________________________________    Activator                                                                            Non-volatile fluid                                                     Composition                                                                          carrier                                                                1      dipropylene glycol                                                                         0.2                                                                              BBTS                                                                              ethyl cyanoacrylate                                       dibenzoate          (rubber containing)                                2      dipropylene glycol                                                                         0.2                                                                              BBTS                                                                              ethyl cyanoacrylate                                       dibenzoate          (gel with silica)                                  3      dipropylene glycol                                                                         0.4                                                                              BBTS                                                                              ethyl cyanoacrylate                                       dibenzoate          (rubber containing)                                4      dipropylene glycol                                                                         0.4                                                                              BBTS                                                                              ethyl cyanoacrylate                                       dibenzoate          (gel with silica)                                  5      dipropylene glycol                                                                         0.5                                                                              BBTS                                                                              ethyl cyanoacrylate                                       dibenzoate          (gel with silica)                                  6      dipropylene glycol                                                                         0.5                                                                              BBTS                                                                              ethyl cyanoacrylate                                       dibenzoate          (with thickener)                                   7      phenethyl acetate                                                                          0.5                                                                              BBTS                                                                              ethyl cyanoacrylate                                                           (gel with silica)                                  8      phenethyl acetate                                                                          0.5                                                                              BBTS                                                                              ethyl cyanoacrylate                                                           (with thickener)                                   9      linalyl acetate                                                                            0.8                                                                              DMPT                                                                              ethyl cyanoacrylate                                                           (gel with silica)                                  10     linalyl acetate                                                                            0.8                                                                              DMPT                                                                              ethyl cyanoacrylate                                                           (with thickener)                                   11     linalyl acetate                                                                            0.5                                                                              DMPT                                                                              ethyl cyanoacrylate                                                           (gel with silica)                                  12     linalyl acetate                                                                            0.5                                                                              DMPT                                                                              ethyl cyanoacrylate                                                           (with thickener)                                   13     1:1 linalyl/phenbutyl                                                                      0.5                                                                              DMPT                                                                              ethyl cyanoacrylate                                       acetate             (gel with silica)                                  14     1:1 linalyl/phenbutyl                                                                      0.5                                                                              DMPT                                                                              ethyl cyanoacrylate                                       acetate             (with thickener)                                   Prior Art                                                                            Volatile Solvent Carrier                                               15     FREON TA     0.75                                                                             DMPT                                                                              ethyl cyanoacrylate                                                           (gel with silica)                                  16     FREON TA     0.75                                                                             DMPT                                                                              ethyl cyanoacrylate                                                           (with thickener)                                   17     FREON TA     0.5                                                                              DMPT                                                                              ethyl cyanoacrylate                                                           (with thickener)                                   18     heptane      0.2                                                                              BBTS                                                                              ethyl cyanoacrylate                                                           (rubber containing)                                19     heptane      0.2                                                                              BBTS                                                                              ethyl cyanoacrylate                                                           (gel with silica)                                  __________________________________________________________________________     BBTS -- Nt-butyl-2-benzothiazolesulfenamide                                   DMPT -- dimethylp-toluidine                                                   Freon TA -- Dupont registered tradename for a mixture of                      trifluorochlorocabon113 with 10% acetone.                                

Compositions 15-18 represent conventional volatile, ozone-depletingsolvents used to carry the active component. As shown in the table,various percents of the amine active component were included in thecompositions. The column labeled "Adhesive Type" lists the type ofcyanoacrylate used in combination with the activator composition to bondgrit-blasted, steel lapshears together for tensile-shear testing.Subsequent to grit-blasting, the lapshear specimens were brushed withthe respective activator compositions and the indicated adhesive appliedusing a 10 mil bondline gap. All cure was effectuated at roomtemperature. Bond strength tests were performed using standard ASTMprocedures. These tests were performed at various time periodssubsequent to initial mating of the lapshear parts, as well assubsequent to heat aging. The results are indicated in Table 2 below.

                                      TABLE 2                                     __________________________________________________________________________    CYANOACRYLATE ADHESIVE TENSILE BOND STRENGTH (PSI)                                     2 HOURS AT                                                                              24 HOURS AT                                                         ROOM      ROOM      1 WEEK AT                                                                            2 WEEKS AT                                         TEMPERATURE                                                                             TEMPERATURE                                                                             60° C.**                                                                      60° C.**                           __________________________________________________________________________    INVENTIVE                                                                     ACTIVATOR                                                                     COMPOSITION                                                                   1        --        2339.33   2496.67                                                                              2718.00                                   2        --        2590.67   2045.33                                                                              2613.33                                   3        --        1866.00   2235.33                                                                              2709.33                                   4        --        1512.00   1462.00                                                                              1948.00                                   5        1244      --        1633   --                                        6        *1068     --        *1589  --                                                 1471      --        1474   --                                        7        2464      --        1587   --                                        8        *2528     --        *2544  --                                                 1549      --        1810   --                                        9        1340      --        1227   --                                        10       1990      --        1873   --                                        11       1381      --        1352   --                                        12       *1465     --        *1481  --                                                 1711      --        1852   --                                        13       2078      --        1571   --                                        14       *1728     --        *1595  --                                                 1572      --        1709   --                                        PRIOR ART                                                                     ACTIVATOR                                                                     COMPOSITION                                                                   15       2134      --        1892   --                                        16       2380      --        2672   --                                        17       1483      --        2221   --                                        18       --        3003.33   3794.00                                                                              2932.00                                   19       --        1976.67   1887.33                                                                              1710.67                                   __________________________________________________________________________     * -- more than one test conducted                                             ** -- cured at room temperature 24 hours prior to aging                  

As evidenced by Table 2 above, cyanoacrylate adhesive compositions, whenused in conjunction with the inventive adhesive promoter compositions,exhibit tensile bond strengths comparable to those results obtained whentraditional volatile, ozone-depleting solvents are used in the promotercompositions. In certain instances, bond strengths increased after aging(compositions 1-4). In other instances, tensile bond strengths obtainedafter twenty-four hours of cure were lower than those taken after twohours. This is believed to be due in part to molecular adjustment whichis known to occur when amine accelerating actives are used incombination with cyanoacrylate adhesives. As shown in the table, tensilebond strengths subsequently increase, in some instances substantially,after heat aging.

To demonstrate the utility of the inventive adhesive promotercompositions on a variety of plastic substrates, various plasticsurfaces were coated with the fluid carrier portion of the adhesivepromoter composition to determine its effect, if any, on the plastic. Inparticular, the fluid carrier was brushed on the plastic surface andobserved for any visible effect such as clouding, etching, or crazing ofthe plastic. Compositions 1, 7, and 9 represent fluid carriers of thepresent invention. Compositions 20, 21, and 22 represent conventionalvolatile solvent carriers and are dipentene, terpenes and acetone,respectively. The results are shown on Table 3 below.

                  TABLE 3                                                         ______________________________________                                        EFFECT OF FLUID CARRIER ON VARIOUS                                            PLASTIC SUBSTRATES                                                                            Inventive                                                                     Non-volatile                                                                           Prior Art                                                            carrier  Solvents                                             PLASTIC SUBSTRATE 1     7     9    20   21  22                                ______________________________________                                        Polycarbonate (PC)                                                                              X     O     X    X    X   O                                 Prevex* (polyphenylene ether                                                                    X     O     X    X    X   X                                 alloy)                                                                        Supec* (polyphenylene sulfide)                                                                  X     X     X    X    X   X                                 Noryl* (polyphenylene oxide)                                                                    X     X     O    O    O   O                                 Ultem*            X     X     X    X    X   X                                 Nylon             X     X     X    X    X   X                                 Melamine          X     X     X    X    X   X                                 Delrin* (polyacetal)                                                                            X     X     X    X    X   X                                 Xenoy*            X     O     X    X    X   O                                 Polycarbonate/polybuytlene-                                                   terephthalate (PC/PBT)                                                        Valox* ((PBT)     X     X     X    X    X   X                                 Acrylic           X     O     X    X    X   O                                 Acrylonitrile Butadiene Styrene                                                                 X     O     X    X    X   O                                 Cellulose Acetate X     X     X    X    X   O                                 Ethylene Vinyl Acetate                                                                          X     X     X    X    X   X                                 Ionomer           X     X     X    X    X   X                                 Polyallomer       X     X     X    X    X   X                                 Polyaryl Ether    X     O     X    X    X   O                                 Polybutylene      X     X     O    O    O   X                                 Polymethylpentene X     X     X    X    X   X                                 Polystyrene       X     O     O    O    O   O                                 Polysulfone       X     X     X    X    X   X                                 Polyvinyl Chloride (PVC)                                                                        X     O     X    X    X   O                                 Styrene Acrylonitrile                                                                           X     O     X    X    X   O                                 Styrene Butadiene O     O     O    O    O   O                                 Thermoplastic Polyester                                                                         X     O     X    X    X   O                                 Urethane Elastomer                                                                              O     X     X    X    X   O                                 ______________________________________                                         X indicates the fluid had no visible effect on plastic                        O indicates the fluid had a visible effect on plastic, with clouding,         etching or crazing                                                            *Trademark                                                               

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention and all suchmodifications are intended to be included within the scope of thefollowing claims.

What is claimed is:
 1. An adhesive promoter composition for promotingcure and/or enhancing adhesion of an adhesive composition, said adhesivepromoter composition comprising:(i) a carrier which remains fluid atroom temperature and is an ester having a boiling point of about 100° C.or more, said ester being selected form the group consisting of anacetic ester of a C₂ -C₁₈ alkenyl or aryl alcohol, an acetic ester of C₃-C₁₈ allyl alcohol, an acetic ester of C₇ -C₁₈ alkylaryl alcohol, anacetic ester of C₇ -C₁₈ arylalkyl alcohol and mixtures thereof, saidcarrier remaining present during cure of said adhesive composition, and(ii) an adhesive promoter capable of promoting the cure and/or enhancingadhesion of said adhesive composition and being miscible in said fluidcarrier.
 2. The composition of claim 1 wherein the carrier has at leastone unsaturated bond present.
 3. The composition of claim 1 wherein theadhesive promoter component is a base.
 4. The composition of claim 3wherein the adhesive promoter component is an amine-containing compound.5. The composition of claim 4 wherein the amine-containing compound isselected from the group consisting of N,N-dimethyl-p-toluidine,t-butyl-2-benzothiazolesulfenamide, N-oxydiethylenebenzothiazole-2-sulfenamide, 2,2'-(p-tolylimino)diethanol-(hydroxyethyl-p-toluidine) and mixtures thereof.
 6. Thecomposition of claim 4 wherein the amine-containing compound is presentin amounts of about 0.01% to about 10% by weight.
 7. The composition ofclaim 5 wherein the amine-containing compound is present in amounts ofabout 0.5% to about 10% by weight.
 8. The composition of claim 1 whereinsaid adhesive promoter component is an organometallic substance.
 9. Anadhesive promoter composition for promoting cure and/or enhancingadhesion of an adhesive composition, said adhesive promoter compositioncomprising:(i) a fluid carrier selected from the group consisting oflinalyl acetate, phenethyl acetate, diethyl acetate, dipropyl acetate,dibutyl phthalate, dioctyl phthalate and mixtures thereof, and (ii) anadhesive promoter capable of promoting the cure and/or enhancingadhesion of said adhesive composition and being miscible in said fluidcarrier.
 10. An adhesive promoter composition for promoting cure and/orenhancing adhesion of and adhesive composition, said adhesive promotercomposition comprising:(i) a fluid carrier comprising a benzoic diesterof an alkyl glycol having the formula OH--(C_(x) H_(2x) O)_(n) --Hwherein x is 2-3 and n may be 1 up to 10 provided the glycol remainsfluid at room temperature, (ii) an adhesive promoter capable ofpromoting the cure and/or enhancing adhesion of said adhesivecomposition and being miscible in said fluid carrier.
 11. Thecomposition of claim 10 wherein the fluid carrier is selecting from thegroup consisting of ethylene glycol dibenzoate, diethylene glycoldibenzoate, propylene glycol dibenzoate, dipropylene glycol dibenzoateand mixtures thereof.
 12. A method of bonding substrate surfaces with anadhesive composition consisting essentially of:treating a surface of atleast one of said substrates with an adhesive promoter compositioncomprising a fluid carrier which remains present during the cure of saidadhesive composition, said fluid carrier being selected from the groupconsisting of an acetic ester of a C₂ -C₁₈ alkenyl or aryl alcohol, anacetic ester of C₃ -C₁₈ allyl alcohols, an acetic ester of C₇ -C₁₈alkylaryl alcohol, an acetic ester of C₇ -C₁₈ arylalkyl alcohol andmixtures thereof, and an adhesive promoter component which is capable ofpromoting the cure and/or enhancing adhesion of said adhesive and ismiscible in said fluid carrier, applying an adhesive composition to thesurface of at least one of the substrates, and bonding said substratesurfaces by placing them in contact with each other prior to evaporationof said fluid carrier.
 13. The method of claim 12 wherein the fluidcarrier is selected from the group consisting of acetic ester having aboiling point of about 100° C. or greater and which remains liquid atroom temperature.
 14. The method of claim 13 wherein the fluid carrierhas at least one unsaturated bond present.
 15. The method of claim 12wherein said adhesive promoter component is an organometallic substance.16. A method of bonding substrate surfaces with an adhesive compositionconsisting essentially of:treating a surface of at least one of saidsubstrates with an adhesive promoter composition comprising a fluidcarrier which remains present during the cure of said adhesivecomposition, said fluid carrier being selected from the group consistingof linalyl acetate, diethyl phthalate, dipropyl phthalate, dibutylphthalate, dioctyl phthalate, phenethyl acetate and mixtures thereof,and an adhesive promoter component which is capable of promoting thecure and/or enhancing adhesion of said adhesive and is miscible in saidfluid carrier, applying an adhesive composition to the surface of atleast one of the substrates, and bonding said substrate surfaces byplacing them in contact with each other prior to evaporation of saidfluid carrier.
 17. The method of claim 16 wherein the adhesive promoteris an organometallic substance.
 18. A method of bonding substratesurfaces with an adhesive composition consisting essentially of:treatinga surface of at least one of said substrates with an adhesive promotercomposition comprising a fluid carrier which remains present during thecure of said adhesive composition, wherein the fluid carrier is abenzoic diester of an alkyl glycol, and an adhesive promoter componentwhich is capable of promoting the cure and/or enhancing adhesion of saidadhesive and is miscible in said fluid carrier, applying an adhesivecomposition to the surface of at least one of the substrates, andbonding said substrate surfaces by placing them in contact with eachother prior to evaporation of said fluid carrier.
 19. The method ofclaim 18 wherein the fluid carrier is selected from the group consistingof ethylene glycol dibenzoate, diethylene glycol dibenzoate, propyleneglycol dibenzoate, dibenzoate, dipropylene glycol dibenzoate andmixtures thereof.
 20. The method of claim 18 wherein the adhesivepromoter component is a base.
 21. The method of claim 20 wherein theadhesive promoter component is an amine-containing compound.
 22. Themethod of claim 21 wherein the amine-containing compound is selectedfrom the group consisting of N,N-dimethyl-p-toluidine,t-butyl-2-benzothiazolesulfenamide, N-oxydiethylenebenzothiazole-2-sulfenamide,2,2'-(p-tolylimino)diethanol(hydroxyethyl-p-toluidine) and mixturesthereof.
 23. The method of claim 22 wherein the amine-containingcompound is present in amounts of about 0.01% to about 10% by weight.24. The method of claim 23 wherein the amine-containing compound ispresent in amounts of about 0.5% to about 10% by weight.
 25. An adhesivekit comprising:(i) an adhesive promoter composition comprising a fluidcarrier which remains present during the cure of an adhesivecomposition, said fluid carrier being selected from the group consistingof an acetic ester of a C₂ -C₁₈ alkenyl or aryl alcohol, an acetic esterof C₃ -C₁₈ allyl alcohols, an acetic ester of C₇ -C₁₈ alkylaryl alcohol,an acetic ester of C₇ -C₁₈ arylalkyl alcohol, linalyl acetate, diethylphthalate, dipropyl phthalate, dibutyl phthalate, dioctyl phthalate,phenethyl acetate and mixtures thereof, and an adhesive promotercomponent which is miscible in said fluid carrier and promotes the cureand/or enhances adhesion of said adhesive composition; and (ii) anadhesive component the cure of which is promoted by said adhesivepromoter composition.